The invention pertains to methods of forming materials comprising tungsten and nitrogen, and in an exemplary application pertains to methods of forming capacitors.
Tungsten nitride has properties which render it particularly suitable for utilization in integrated circuitry. For instance, tungsten nitride is found to exhibit better or equivalent electrical properties when compared to such commonly utilized compositions as, for example, TiN. Further, tungsten nitride retains its good electrical properties after being subjected to relatively high temperature processing, such as a polysilicon anneal or borophosphosilicate glass (BPSG) reflow.
Tungsten nitride materials can be formed by, for example, chemical vapor deposition processes, such as, for example, plasma enhanced chemical vapor deposition (PECVD). The tungsten nitride materials formed by such methods can have good step coverage over an underlying substrate and be continuous, particularly if formed at lower working ends of temperature and plasma power ranges. However, utilization of such tungsten nitride materials has been limited due to difficulties in working with the materials. Specifically, tungsten nitride can peel, and/or bubble, and/or crack when exposed to high temperature processing (such as, for example, the greater than 800xc2x0 C. processing associated with anneal steps). The peeling, cracking and bubbling lead to a non-continuous film. It would be desirable to develop methods of forming materials comprising tungsten nitride which overcome problems associated with tungsten nitride exposure to high temperature processing conditions.
In one aspect, the invention includes a method of forming a material comprising tungsten and nitrogen. A layer comprising tungsten and nitrogen is deposited over a substrate. Subsequently, and in a separate step from the depositing, the layer comprising tungsten and nitrogen is exposed to a nitrogen-containing plasma.
In another aspect, the invention includes a method of forming a capacitor. A first electrical node is formed and a dielectric layer is formed over the first electrical node. A second electrical node is formed and separated from the first electrical node by the dielectric layer. A layer comprising tungsten and nitrogen is provided between the dielectric layer and one of the electrical nodes. The providing the layer comprising tungsten and nitrogen includes: a) depositing a layer comprising tungsten and nitrogen; and b) in a separate step from the depositing, exposing the layer comprising tungsten and nitrogen to a nitrogen-containing plasma.